New Method of Fortification by Sluices

Regarding the second type of Sluices Sluices are water control gates; here the author describes what we now call a "tide gate" or "clapper valve.", used for drying waterlogged low-lying Lands, it is most conveniently done with Sluices having pointed gates original: "portes poinctues". These are miter gates that meet at an angle, similar to those seen on modern canal locks. (which are also called turning gates) placed beneath the Dikes original: "Dicques". Embankments or levees designed to hold back the sea or rivers., the plan of which is demonstrated in the following 2nd Figure. These are designed so that when the exterior water is lower, the gates open by themselves to let the water out; but when the exterior water becomes higher, they close by themselves. And although some use gates hoisted upward for this purpose, like those in the 1st Figure, they are not the most convenient for such an end. It is a burdensome thing, where there is a daily ebb and flow original: "flux & reflux". The rising and falling of the tide., to observe the time day and night to open those gates; furthermore, hoisting original: "guindement". The act of raising a heavy gate using a windlass or winch. them upward is a laborious task. In addition, they cannot be made wide enough to empty much water because they would be too heavy to hoist. It is true that turning gates also have their inconveniences: first, large Ships with their masts upright cannot pass through because of the Dike that sits above them; secondly, they hardly deepen the Harbors, because the water does not fall from above onto a dry bottom as with the first kind, but rather flows out gradually.

A technical plan view diagram of a sluice or lock structure labeled "2 FORM." It shows a stone-walled channel built into an embankment, featuring a pair of "pointed gates" (miter gates) that meet in a V-shape. The masonry of the walls is detailed with hatching, and the surrounding ground is indicated with stippling. The diagram illustrates the second type of sluice discussed in the text, designed to operate automatically with the pressure of the tide or water flow.

As for the third type of Sluices, used for passing Ships with their masts upright, this is done with two pairs of pointed gates. These are not placed beneath the Dike like those of the second type, but within the Dike itself and as high as the Dike, so that they serve as Dikes from the bottom to the top to resist all high waters. The plan is shown in the following 3rd Figure, in which the first pair is A, the second pair B, containing between them a ship receptacle original: "receptacle de Navires". This is a lock chamber, the space between two sets of gates used to raise or lower vessels., with two small sluices built inside the walls, marked C D E and F G H. Alternatively, one can make small hoisting doors within the large pointed gates. Their use is thus: when a Ship with an upright mast wishes to enter, as from A toward B, and the exterior water is higher than the interior, one fills the receptacle with water through the small sluice C D E. When the water is at the same height as the exterior water, the two gates at B are held closed, but those at A can be opened by hand, and the Ships which must—